U.S. Pat. No. 5,193,065 is known in the state of the art. This patent describes a system for ordering and distributing materials in a manufacturing environment. A manufacturing station stores and uses the material and produces a first signal of material shortage in response to consumption of a predetermined quantity of material normally found at a manufacturing station. An intelligent stocking unit stocks the material. A computer system receives the first material shortage signal and responds by searching the storage unit, producing a material-transfer command signal corresponding to the presence of material in the stocking unit and producing a shipment triggering signal corresponding to the absence of material in the stocking unit. A microcomputer generates a program for the material. A logical device receives the shipment-triggering signal and generates a shortage signal in reaction to the shipment-triggering signal and the program for the material. This method of pulled-flow production management solely takes into account information transmitted from downstream to upstream.
Also known in the state of the art is the kanban method described, for example, in Orthogon GmbH “IKS-Integrated Kanban System, Introduction (version 2.2)”. The fundamental principles of kanban (or pulled-flow operating on stocks) are: taking into account consumption by reconstitution of the real consumption; and anticipation of short-term requirements by calculation of the average daily consumption (ADC). Kanban is thus a signal (label) which informs a supplier that it must manufacture again or deliver the quantity really consumed by its client.
The principal drawbacks of this system are: it is a manual system incapable of monitoring the number of labels in circulation and of signaling possible losses of labels; it is a rigid system because the number of labels is not recalculated as a function of real and instantaneous demand; transmission of orders to the supplier is not automated and, therefore, not guaranteed; and in the case of use in internal flows (internal clients and suppliers), the emission of the resupplying order does not modify the calculation of the work charges. A great risk is that this reconstitution of consumption which does not take into account the fluctuation of future demand can generate stocks that no longer correspond to the demand.